The subject invention relates to a rubber bonded anchor pin of a brake assembly for a vehicle, particularly a heavy vehicle such as a truck or tractor-trailer.
One type of known vehicle brake assembly incorporates a brake drum, mounting brackets including conventional anchor pins, brake shoes rotatably supported by the anchor pins for rotation of the brake shoes relative to the mounting brackets, an air chamber, and return springs.
When an operator of a vehicle activates the brake assembly, air is introduced into the air chamber which forces the brake shoes, from an initial position, into contact with the brake drum to slow or completely stop the vehicle. When the operator of the vehicle deactivates the brake assembly, the return springs draw the brake shoes back to their initial position. When moving to contact the brake drum, and in returning to the initial position, the brake shoes rotate about the anchor pins relative to the mounting bracket.
The conventional anchor pins encompass two general designs. One known anchor pin is a solid metal design. A second known anchor pin is a two-piece roller design. In the solid metal design, the anchor pin is fixed relative to the mounting bracket, and under normal conditions, the brake shoe rotates about the anchor pin. In the two-piece roller design, the anchor pin rotates relative to the mounting bracket within a sleeve that is pressed into the mounting bracket, and under normal conditions, the brake shoe and anchor pin rotate relative to the mounting bracket. Both designs are susceptible to corrosion problems resulting from rust, road debris, heat, mechanical wear, and other road effects realized throughout the normal duty of the vehicle. For instance, in the solid metal design, the anchor pin can corrosively bond to the mounting bracket primarily due to heat and rust. The anchor pin in the two-piece roller design is similarly susceptible to corrosive bonding due to heat and rust. Furthermore, in either design, the brake shoe can corrosively bond directly to the anchor pin. If the brake shoe bonds to the anchor pin, and the anchor pin is corrosively bonded to the mounting bracket, then the brake shoe cannot rotate about the anchor pin.
Due to the inefficiencies identified in conventional brake assemblies that incorporate conventional anchor pins, it is desirable to implement a brake assembly that endures corrosive road effects by disposing a rubber layer between the anchor pin and the mounting bracket to permit rotation of the brake shoe about the mounting bracket in the event the brake shoe becomes corrosively bonded to the anchor pin.
A vehicle brake assembly for enduring corrosive road effects is disclosed. The brake assembly includes a mounting bracket including a bore. An anchor pin extends through the bore of the mounting bracket. The anchor pin includes first and second end portions and an outer surface. The brake assembly includes a brake shoe rotatably supported on the anchor pin for rotation relative to the mounting bracket. A rubber layer is disposed between the outer surface of the anchor pin and the bore of the mounting bracket.
The rubber layer, and the incorporated flexural stiffness of the rubber layer, permits rotation of the brake shoe about the mounting bracket in the event the brake shoe becomes corrosively bonded to the pin. Additionally, the rubber layer eliminates all metal-to-metal contact between the outer surface of the anchor pin and the bore of the mounting bracket thereby preventing the outer surface of the anchor pin from corrosively bonding to the bore.
Accordingly, the subject invention provides a brake assembly for a vehicle that endures corrosive road effects by disposing a rubber layer between the anchor pin and the mounting bracket. Consequently, the anchor pin does not bond to the bore, and in the event the brake shoe does become corrosively bonded to the anchor pin, rotation of the brake shoe about the mounting bracket is still permitted and proper operation of the brake assembly is maintained.